Derivatives of 1,7-dihydro-2H-pyrazolo{8 4{40 ,3{40 :5,6{9 pyrido{8 4,3-D{9 pyrimidine-2,4-(3H)-diones

ABSTRACT

The new derivatives of 1,7-Dihydro-2H-pyrazolo-(4&#39;&#39;,3&#39;&#39;: 5,6)pyrido(4,3-d)pyrimidine-2,4-(3H)-diones have the general formula   R1 is hydrogen, lower alkyl, phenyl or phenyl-lower alkyl. R2 is hydrogen, lower alkyl or phenyl. R3 is hydrogen, lower alkyl, phenyl, phenyl-lower alkyl, (lower alkyl)amino-lower alkyl or di(lower alkyl)amino-lower alkyl. R4 is lower alkyl, phenyl, lower alkyl-phenyl or cyclo lower alkyl. R5 is hydrogen or lower alkyl. They are useful as anti-inflammatory agents and central nervous system depressants. In addition, this type of compound increases the intracellular concentration of adenosine-3&#39;&#39;,5-cyclic monophosphate.

United States Patent [191 Denzel et al.

[451 July 8,1975

[ DERIVATIVES 0F 1,7-DIHYDRO-2H- PYRAZOLO[4,3:5,6]PYRIDO[4,3- D]PYRIMIDlNE-2,4-(3H)-DIONES [75] Inventors: Theodor Denzel, Nurnberg; Hans Hoehn, Tegemheim, both of Germany [73] Assignee: E. R. Squibb & Sons, Inc.,

Princeton, NJ.

[22] Filed: Jan. 28, 1974 [21] Appl. No.: 437,461

[52] U.S. Cl 260/256.4 F; 424/251 [51] Int. Cl C07d 51/42 [58] Field of Search 260/2564 1F Primary Examiner-Donald G. Daus Assistant ExaminerJames l-l. Turnipseed Attorney, Agent, or FirmLawrence S. Levinson; Merle J. Smith [57] ABSTRACT The new derivatives of 1,7-Dihydro-2H-pyrazolo- [4,3'15,6]pyrido[4,3-d]pyrimidine-2,4-(3H)-diones have the general formula They are useful as anti-inflammatory agents and central nervous system depressants. In addition, this type of compound increases the intracellular concentration of adenosine-3,5-cyclic monophosphate.

13 Claims, N0 Drawings SUMMARY OF THE INVENTION This invention relates to new derivatives of 1,7- dihydro-Zll-I-pyrazoloM,3:5,6]pyrido[4,3-d]pyrimidine-2,4-(3I-l)-diones. These new compounds have the general formula (I) The symbols have the following meanings in formula I and throughout this specification.

IR, is hydrogen, lower alkyl, phenyl or phenyl lower alkyl.

R is hydrogen, lower alkyl or phenyl.

R is hydrogen, lower alkyl, phenyl, phenyl lower alkyl, (lower alkyl)amino-lower alkyl or di(lower alkyl)amino-lower alkyl.

IR, is lower alkyl, phenyl, lower alkyl-phenyl or cyclo lower alkyl.

R is hydrogen or lower alkyl.

The lower alkyl groups are straight or branched chain hydrocarbon radicals of up to seven carbons like methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl and the like. The one to four carbon alkyl groups are preferred, especially the one and two carbon members. The cyclo-lower alkyl groups are the three to six carbon alicyclics cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl, preferably the last two.

Preferred compounds of formula I are those in which R, is hydrogen or lower alkyl, especially ethyl; R and R is hydrogen or methyl, especially hydrogen; R is lower alkyl or di(lower alkyl)amino-lower alkyl, especially dimethylaminopropyl, R is lower alkyl, espe cially methyl, phenyl or cyclohexyl.

DETAILED DESCRIPTION The new compounds of formula I are produced from compounds of the formula OC lI'I COOalkyl R 2 l IO N\N N R (US. Pat. No. 3,773,777, Nov. 20, 1973). The compound of formula II is treated with ammonia at about 5 120C. for 10 hours in an autoclave, producing a compound of the formula (III) COOalkyl Compounds of formula I wherein R is hydrogen, i.e.,

H l R NkN/ are obtained by reaction of a compound of formula III with an isocyanate of the formula Oalkyl COOalkyl wherein R is a heterocyclic like furyl, pyridyl, pyrimidyl, pyrazinyl or the like. This compound of formula V is processed in the same manner as the product of formula lll, e.g., by treatment with ammonia, reaction with an isocyanate of formula IV and alkylation with the appropriate alkyl halide- At this point a compound of the formula is obtained and this is now oxidized with an oxidizing agent like selenium dioxide in a high boiling solvent like dimethyleneglycol dimethylether at about 160C. to produce a product of formula I wherein R is hydrogen.

The new compounds of this invention are central nervous system depressants and may be used as tranquilizers or ataractic agents'for the relief of anxiety and tension states, for example, in mice, cats, rats, dogs and other mammalian species, in the same manner as chlordiazepoxide. For this purpose a compound or mixture of compounds of formula I is administered orally or parenterally in a conventional dosage form such as tablet, capsule, injectable or the like. A single dose, or preferably 2 to 4 divided daily doses, provided on a basis of about 3 to 50 mg. per kilogram per day, preferably about 3 to 15 mg. per kilogram per day, is appropriate. These may be conventionally formulated in an oral or parenteral dosage form by compounding about to 250 mg. per unit of dosage with conventional vehicle, excipient, binder, perservative, stabilizer, flavor or the like as called for by accepted pharmaceutical practice.

The new compounds also increase the intracellular concentration of adenosine-3',5'-cyclic monophosphate, and thus, by the administration of about 1 to 100 mg./kg./day, preferably about 10 to 50 mg./kg., in single or two to four divided doses in conventional oral or parenteral dosage forms such as those described above they may be used to alleviate the symptoms of asthma.

The new compounds of this invention, in addition, have antiinflammatory properties and are useful, for example, to reduce local inflammatory conditions such as those of an edematous nature or resulting from proliferation of connective tissue in various mammalian species such as rats, dogs and the like when given orally in dosages of about 5 to 50 mg./kg./day, preferably 5 to 25 mg./kg./day, in single or 2 to 4 divided doses, as indicated by the carageenan edema assay in rats. The activev substance can be utilized in compositions such as tablets, capsules, solutions or suspensions containing up to about 300 mg. per unit of dosage of a compound or mixture of compounds of formula I. They are compounded in conventional manner with a physiologically acceptable vehicle or carrier, excipient, binder, preserresidual vative, stabilizer, flavor, etc. as called for by accepted pharmaceutical practice. Topical preparations containing about 0.03 to 3 percent by weight of active substance in a lotion, salve or cream may also be used.

The following examples are illustrative of the invention. All temperatures are on the centigrade scale.

EXAMPLE 1 a. 4-Aminol -ethyll H-pyrazolo[3 ,4-b]pyn'dine-5- carboxylic acid ethyl ester 10.4 g. of 4 .ethoxy-l-ethyl-lH-pyrazolo[3,4- b]pyridine-S-carboxylic acid ethyl ester (0.04 mol.) and 50 ml. of an alcoholic solution of ammonia (56.5 g. ammonia in 1000 ml. ethanol) are heated in an autoclave at 65 for 15 hours. After cooling, the solid 4- amino- 1 -ethyl-l H-pyrazolo[ 3,4-b]pyridine-5- carboxylic acid ethyl ester is filtered off and recrystallized from ethanol, yield, 7.4 g. m.p. l8l-l 82.

b. 7-Eth yl-1,7-dihydro-3-methyl-2H- pyrazolo[4,3 ':5,6]pyrido-[4,3-d]pyrimidine-2,4-

(3H )-dione 234 g. of 4 amino-l-ethyl-lH-pyrazolo[3,4- b]pyridine-S-carboxylic acid ethyl ester (1 mol.) are slowly added to a suspension of 24.4 g. of sodium hydride in anhydrous dioxane at reflux temperature. After the addition is completed, the mixture is stirred for one hour. 57 g. of methyl isocyanate are slowly added dropwise so that the mixture gently refluxes. Heating is continued for 5 hours. After cooling, the product is acidified by adding glacial acetic acid and the precipitated 7-ethyl-l,7-dihydro-3-methyl-2H- pyrazolo[4',3:5,6]pyrido[4,3-d]-pyrimidine-2,4- (3H)-dione is filtered off and recrystallized from dimethylformamide, yield, 211 g. (86%); m.p. 33l-332.

EXAMPLE 2 EXAMPLE 3 7-Ethyl-l ,7-dihydro-3-phenyl-2H- pyrazolo[4',3 :5,6]pyrido[4,3-d]-pyrimidine-2,4-

(3H)-dione 23.4 g. of 4-amino-l-ethyl-lH-pyrazolo[3,4- b]pyridine-S-carboxylic acid ethyl ester (0.] mol.) are slowly added to 2.6 g. of sodium hydride in ml. of anhydrous dioxane. The mixture is refluxed with stirring for about 1 hour. At this time, 12 g. of phenyl isocyanate are added dropwise and the mixture heated at reflux temperature for additional hours. The solution is acidified with acetic acid and the precipitated 7-etl'1yl-l,7-dihydro-3-phenyl-2H- pyrazolo[4 ',3 ':5 ,6]pyrido-[4,3-d]pyrimidine-2,4-

(3l-ll )-dione is filtered and recrystallized from dimethylformamide, yield, 21.8 g. (71%), mp 350.

EXAMPLE 4 EXAMPLE 5 3-Cyclohexyl-7-ethyl-1,7-dihydro-2l-lpyrazolo[4',3':5,6]pyrido[4,3-d]pyrimidine-2,4(3H)- dione By substituting an equivalent amount of cyclohexyl isocyanate in the procedure of Example 3, 3- cycl0hexyl-7-ethyl-1,7-dihydro-2ll-lpyrazolo[4',3:5,6]pyrido[4,3-d]pyrimidine-2,4-(3H)- dione is obtained, m.p. 304-305.

EXAMPLE 6 3-Cyclohexyl-1,7-diethyl-1,7-dihydro-2l-lpyrazolo[4',3 '15 ,6]-pyrido[4,3-d]pyrimidine-2,4- (3ll-l)-dione By treatment of 3-cyclohexyl-7-ethyl-l,7dihydro- 2l-lpyrazolo[4',3':5,6]pyrido[4,3-d]pyrimidine-2,4- (3l-l)-di0ne with ethyl iodide according to the procedure of Example 4, 3-cyclohexyl-l,7-diethyl-1,7- dihydro-2l-l-pyrazolo[40,3'25,6]-pyrido[4,3-d]pyrimidine-2,4-(3ll-l)-dione, m.p. 169l70, is obtained.

EXAMPLE 7 7-Ethyl-l ,7-dihydro-3-methyl-1-(3-methylbutyl)-2l-lpyrazolo [4,3 :5 ,6 ]pyrido[4,3-d]pyrimidine-2,4-( 31-1 )-dione By treating the product of Example 1 b with isopentyl iodide as in Example 4, 7ethyl-1,7-dihydro-3-methyl- 1-(3-methylbutyl)-2l-l-pyrazolo[4',3':5,6]pyrido[4,3- d]pyrimidine-2,4-(3lll)-di0ne, m.p. 141143, is obtained.

EXAMPLE 8 By substituting the product of Example 1 b for the starting material in the procedure of Example 4, 1,7- diethyl-l ,7-dihydro-3-methyl-2l-lpyrazolo[4,3:5,6]pyrido[4,3-d]-pyrimidine-2,4- (3H)-di0ne, m.p. 167l68, is obtained.

6 EXAMPLE 9 3-Cyclobutyll ,7-dihydr0-2H- pyrazolo[4' ,3 :5 ,6]pyrido[4,3-d]-pyrimidine-2,4- 5 (3ll-l)-dione By substituting 4-aminol lH-pyrazolo[3 ,4- b]pyridine-5-carboxylic acid ethyl ester for the 4-amino-l-ethyl-1H-pyrazolo 3 ,4-b]pyridine-5- l0 carboxylic acid ethyl ester and cyclobutyl isocyanate for the phenyl isocyanate in the procedure of Example 3, 3-cyclobutyl-1 ,7-dihydro-2H-pyrazolo[4 ,3 :5 ,6]- pyrido[4,3-d]pyrimidine-2,4-(3ll)-dione is obtained.

EXAMPLE 10 By treating the product of Example 9 with benzyl chloride instead of ethyl iodide according to the procedure of Example 4, l-benzyl-3-cyclobutyl-l ,7-dihydro- 2l-l-pyrazolo-[4 ,3 :5 ,6]pyrido[4,3-d]pyrimidine* 2,4(3l-l)-dione is obtained.

EXAMPLE 11 3-Butyl-7-phenyl-1,7-dihydro-2l-lpyrazolo[ ,3 :5 ,6]pyrid0[4,3-d]pyrimidine- 35 2,4(3lll)-dione By treating 4-amino-l-phenyl-llH-pyraZolo[3,4-b]- pyn'dine-S-carboxylic acid ethyl ester with butyl isocyanate as in Example 1b, 3-butyl-7phenyl-l,7-

4O dihydro-2l-l-pyrazolo[4 ,3 :5 ,6]-pyn'do[4,3-d]

pyIimidine-2,4-(3H)-dione is obtained.

EXAMPLE 12 1-[2-(2-Diethylamino)ethyl]-3-butyl-7-phenyl-l ,7-

By treating the product of Example 11 with diethylaminoethyl chloride as in Example 2, 1-[2-(2-diethylamin0)ethyl]-3-butyl-7-phenyl-1 ,7-dihydro-2H- pyrazolo[4 ,3 :5 ,6]pyrido [4,3-d]pyrimidine-2,4(3H)- dione is obtained.

EXAMPLE 13 3-Butyl-1,7-diphenyl-1,7-dihydro-2l-llpyraz0lo[4,3 :5 ,6]pyrido-[4,3-dJpyrimidine-2,4(3 1-1)- dione By treating the product of Example 1 1 with iodobenzene as in Example 4, 3-butyl-1,7-diphenyl-1,7- dihydro-2H-pyrazolo[4 ,3 :5,6]pyrid0[4,3- d]pyrimidine-2,4(3)-dione is obtained.

b]-pyridine--carboxylic acid ethyl ester with phenyl isocyanate as in Example 3, 5,9-diethyl-l,7-dihydro- 3-phenyl-2H-pyrazolo[4' ,3 :5 ,6]pyrido[4,3 -d]- pyrimidine-2,4(3H)-dione is obtained.

EXAMPLE l5 5,9-Diethyl-l ,7-dihydrol -methyl-3-phenyl- 2H- pyrazolo 4 ,3 :5 ,6 ]-pyrido 4,3-d] pyridimidine- 2,4( 3H)-dione By treating the product of Example 14 with methyl iodide by the procedure of Example 4, 5,9-diethyl-l ,7- dihydrol -methyl-3-phenyl-2H- pyrazolo[4,3':5,6]pyrido[4,3-d]-pyrimidine-2,4(3l-l)- dione is obtained.

EXAMPLE l6 3-p-Tolyll ,7-dihydro-2H- pyrazolo[4',3':5,6]pyrido[4,3-d]-pyrimidine-2,4(3H)- dione By substituting 4-aminol H-pyrazolo[ 3 ,4- b]pyridine-5-carboxylic acid methyl ester for the 4- amino-l-ethyl-1H-pyrazolo-[3,4-b]pyridine-5- carboxylic acid ethyl ester and benzyl isocyanate for the p-tolyl isocyanate in the procedure of Example 3, 3-p-tolyl-l ,7-dihydro-2H- pyrazolo[4',3':5,6]pyrido[4,3-d]pyrimidine-2,4(3H)- dione is obtained.

EXAMPLE 17 l-[ 2( Methylamino )ethyl-7-ethyl-l ,7-dihydro-3- methyl-2H-pyrazolo-[4,3':5,6]pyrido[4,3- d]pyrimidine-2,4(3H)-dione By substituting (2-methylamino)ethyl chloride for the 3-(dimethylamino)propyl chloride in the procedure of Example 2,l-[2-(methylamino)ethyl]-7-ethyl-l,7- dihydro-3-methyl-2H-pyrazolo[4,3':5,6]pyrido[4,3- d]pyrimidine-2,4(3l-l)-dione is obtained.

EXAMPLE 18 3,5,9-Triphenyll ,7-dihydro-2H- pyrazolo[4',3':5,6]pyrido [4,3-d]pyrimidine-2,4(3H)-dione By treating 4-amino-3 ,6-diphenyl-1 l-l-pyrazolo-[3 ,4- b]pyridine-5-carboxylic acid ethyl ester with phenyl isocyanate as in Example 3,3,5,9-triphenyl-l,7- dihydro-2H-pyrazolo-[4,3':5,6]pyrido[4,3- d]pyrimidine-2,4(3H)-dione is obtained.

EXAMPLE 19 5 ,9-Dimethyl-l ,7-dihydro-7-ethyl-3- phenyl-2H-pyrazolo[4,3':5,6]-pyrido[4,3- d]pyrimidine-2,4(3H)dione By treating 4-aminol -ethyl-3 ,6-dimethyl-l H- pyrazolo[ 3,4-b]pyridine-S-carboxylic acid methyl ester 8 with phenyl isocyanate as in Example 3 5,9-dimethyll ,7-dihydro-7-ethyl-3-phenyl-2H- pyrazolo[4',3':5,6]pyrido[4,3-d]pyrimidine-2,4(3H)-' dione is obtained.

What is claimed is: n 1. A compound of the formula wherein R, is hydrogen, lower alkyl, phenyl or phenyl-lower alkyl; R is hydrogen, lower alkyl or phenyl; R is hydrogen, lower alkyl, phenyl, phenyl-lower alkyl, (lower alkyl) amino-lower alkyl or di(lower alkyl- )amino -lower alkyl; R is lower alkyl, phenyl, (lower alkyl)-phenyl or three to six carbon cyclo-lower alkyl; and R is hydrogen or lower alkyl, said lower alkyl groups having up to seven carbons.

2. A compound as in claim 1 wherein R, is hydrogen or lower alkyl; R and R is hydrogen or methyl; R is lower alkyl or di(lower)amino-lower alkyl; R, is lower alkyl, phenyl or cycloalkyl.

3. A compound as in claim 1 wherein R, and R each is lower alkyl, R R and R each is hydrogen.

4. The compound as in claim 1 wherein R, is ethyl,

' R R and R each is hydrogen and R is methyl.

5. A compound as in claim 1 wherein R,, R and R, each is lower alkyl and R and R each is hydrogen.

6. The compound as in claim 1 wherein R, is ethyl, R and R each is hydrogen, R is isopentyl and R is methyl.

7. The compound as in claim 1 wherein R, and R each is ethyl, R and R each is hydrogen and R is methyl.

8. A compound as in claim 1 wherein R, and R each is lower alkyl, R, and R each is hydrogen and R is di(- lower alkyl)amino-lower alkyl.

9. The compound as in claim 1 wherein R, is ethyl, R and R each is hydrogen, R is dimethylaminopropyl and R is methyl.

10. A compound as in claim 1 wherein R and R each is lower alkyl, R, and R each is hydrogen and R is phenyl.

1 l. The compound as in claim 10 wherein each lower alkyl group is ethyl.

12. A compound as in claim 1 wherein R, is lower alkyl, R R and R each is hydrogen and R is phenyl.

13. The compound as in claim 12 wherein the lower alkyl group is ethyl. 

1. A COMPOUND OF THE FORMULA
 2. A compound as in claim 1 wherein R1 is hydrogen or lower alkyl; R2 and R5 is hydrogen or methyl; R3 is lower alkyl or di(lower)amino-lower alkyl; R4 is lower alkyl, phenyl or cycloalkyl.
 3. A compound as in claim 1 wherein R1 and R4 each is lower alkyl, R2, R3 and R5 each is hydrogen.
 4. The compound as in claim 1 wherein R1 is ethyl, R2, R3 and R5 each is hydrogen and R4 is methyl.
 5. A compound as in claim 1 wherein R1, R3 and R4 each is lower alkyl and R2 and R5 each is hydrogen.
 6. The compound as in claim 1 wherein R1 is ethyl, R2 and R5 each is hydrogen, R3 is isopentyl and R4 is methyl.
 7. The compound as in claim 1 wherein R1 and R3 each is ethyl, R2 and R5 each is hydrogen and R4 is methyl.
 8. A compound as in claim 1 wherein R1 and R4 each is lower alkyl, R2 and R5 each is hydrogen and R3 is di(lower alkyl)amino-lower alkyl.
 9. The compound as in claim 1 wherein R1 is ethyl, R2 and R5 each is hydrogen, R3 is dimethylaminopropyl and R4 is methyl.
 10. A compound as in claim 1 wherein R1 and R3 each is lower alkyl, R2 and R5 each is hydrogen and R4 is phenyl.
 11. The compound as in claim 10 wherein each lower alkyl group is ethyl.
 12. A compound as in claim 1 wherein R1 is lower alkyl, R2, R3 and R5 each is hydrogen and R4 is phenyl.
 13. The compound as in claim 12 wherein the lower alkyl group is ethyl. 